Nanoscale molecular analysis of photoresist films with massive cluster secondary-ion mass spectrometry

Abstract. We describe a methodology for nanoscale molecular analysis and present its capabilities. The analysis method is based on secondary-ion mass spectrometry with gold nanoparticles (e.g., Au4004+). The methodology presented has unique features that enable nanoscale molecular analysis, namely the method of acquiring the mass spectrum and the nature of the impacting projectile. In the method, a sequence of individual gold nanoparticles (Au4004+) is used to bombard the sample; each impact results in ion emission from an area ∼10–20  nm in diameter. For each of impact of Au4004+, the emitted ions are mass analyzed by time-of-flight mass spectrometry, detected and stored together in one mass spectrum prior to the arrival of the subsequent projectile. Each mass spectrum contains elements and molecules, which are colocalized within ∼10 to 20 nm of one another. Examination of the coemitted ions allows us to test the molecular homogeneity and chemical composition at the nanoscale. We applied this method to a chemically amplified resist before and after exposure and development. After development the method was used to chemically characterize defect sites that were not removed by the developing solution.